Burring tool



A. BRUNNER 'BURRING TOOL June 8, 1937.

Filed June 22, 1936 18 I7 F|G.l.

IN V EN TOR. BRUNN ER ATTORNEY.

Patented June 8, 1937 UNITED srA'rEs 2,083,427 BURRDIG r001.

Albert Brunner, St. Louis, Mo., assignor to Wagner Electric Corporation,St. Louis, Mo., a corporation of Delaware Application .l'une 22, 1936,Serial No. 86,500

13 Claims.

My invention relates to tools and more particularly to portable toolsfor smoothing the rough or burred edge of a drilled or punched opening.

In the manufacture of certain types of cylinder and piston combinationsit is necessary to provide the cylinder wall with a hole or aperture forthe ingress and egress of fluid. This hole is generally formed bydrilling from the ex terior of the cylinder to the interior andconsequently the inner edge of the hole is left with a rough sharp edgecommonly known as a burr. Since this edge is on the interior of thecylinder, the rough edge cannot be conveniently reached and removed byan ordinary punch. If the edge is not removed, it will injure thepacking of the piston during the reciprocation of the pis ton past theopening, a condition which is undesirable. In accordance with myinvention, I have devised a portable burring tool by means of which thesharp inner edges of the type of hole above referred to may be easilyand quickly made smooth.

One of the objects of my invention is to produce a. burring tool whichis especially adapted for smoothing the inner edge of a drilled hole ina cylinder Wall. I

Another object of my invention is to produce a burring tool that issimple, inexpensive, easily operable, and adapted for use with cylindersof different diameters and constructions.

Other objects of my invention will become apparent from the followingdescription taken in connection with the accompanying drawing showingthree embodiments thereof.

In the drawing Figure 1 is a view showing one form of my burring toolbeing employed for smoothing the inner edge of a drilled hole in acylinder; Figure 2 is an enlarged cross-sectional view taken on thelines 22 of Figure '1 showing parts of the tool just prior to the toolbeing operated; Figure 2A is an enlarged crosssectional view showing howthe burring operation is performed; Figure 3 is a View of a modifiedconstruction; and Figure 4 is a view of another modified constructionfor use on a different type of cylinder construction.

Referring to Figures 1, 2, and 2A, the burring tool shown comprises twocooperating levers l and 2 pivoted together at an intermediate point bymeans of a pivot pin 3. The rear ends of the levers are so formed as toprovide handles 4. and 5 for actuation by the hand of an operator andthe forward ends of the levers are formed so as to provide straight arms6 and 1, arm 6 being provided with a projection 8 acting as a stopmember to limit the extent of inward movement of the arms. The extremeend of arm I has formed therein a suitable opening into which is pressfitted a punch member 9 provided with a conical portion [0 and anupstanding projection II, the portion between the conical portion andthe projection being so formed as to provide an annular curvedsurfacefor performing the burring operation of the tool. This punch member isconstructed of a suitable hardened material, as. for example, hardenedtool steel, in order that it may properly perform its function over aconsiderable period of time. The extreme end of arm 6 is also providedwith a suitable opening into which is press fitted an abutment member [2which is preferably made from aluminum although other soft metals andmaterials which will not injure a smooth surface may be employed. Theouter surface l3 of member I2 is curved as shown, the curvature beingsuch that the point of contact of the abutment against asupport willaways be in alignment with the axis of the punch within the limits forwhich the tool is designed.

Inorder to normallymaintain arms 6 and 1 in closed position where armengages projection 8, the handle portion 4 is provided with a projectinglug l4 and handle 5 is provided with a similar projecting lug i5 andpositioned between, these lugs is an expansion spring [6 normallybiasing handles 4 and 5 apart and, consequently, biasing arms 6 and Itogether. One end of the spring is adapted to fit over projection Hi andthe other end over projection l5 in the manner shown.

The inner end of arm 1 adjacent the pivot point of the lever has formedthereon an upstanding projection l'! and threaded through thisprojection is a screw l8 forming an adjustable stop for engaging the endof a cylinder and predetermining the distance the punch member on arm Ican be inserted into the end of the cylinder.

I have shown my tool as being used for burring or smoothing the inneredge of what is known as a compensating port in a master cylinderconstruction used in hydraulic brake systems but it is to be understoodthat this is solely for the purpose of illustration as the tool may beas readily employed for burring the edges of openings in other types ofcylinders or articles. -In the cylinder construction shown cylinder I9is formed with a compensating port 20 which is employed for placing theinterior of the cylinder in communication with the reservoir positioneddirectly above the cylinder and enclosed by wall 2!, only a portion ofwhich is shown. This compensating port is produced by a drillingoperation from the reservoir or exterior side of the cylinder and, as aresult thereof, the inner end of the compensating port or opening 20 isleft with a rough sharp edge commonly referred to as a burr and shownexaggerated at 22 in Figure 2. When the piston and piston packing cup,which operate in cylinder I9 are positioned in the cylinder, theirnormal retracted position is suchthat they are positioned tothe rear ofcompensating port 28. It is'thus seen that if the sharp rough edge 22 isnot removed after the drilling operation is performed, it will cause thepacking to be cut during reciprocationiofi...

openingili. This point is determined by proper adjustment of set, screwi8 which abuts against the end of the cylinder when arms 6 and 1 areinserted in the bore thereof. The position of punch .9 with respecttohole 2|] when the arms are initially inserted in the cylinder is bestshown ,in Figure 2. To now perform the burring operation'or thesmoothing of the sharp edge 22, handles 4 and 5 of thetool are forcedtogether by the hand ofthe operator, thereby causing projection H toenter opening 20 and abutment I2 to engagethe opposite wall of thecylinder and at a point in-alignment with the axis of punch member 9.Pressure onthe handles'will now cause the annular curved surface betweenprojection-l I" and the conical portion ID; tobe Referring to Figure 3,I have shown a slightly modified-=constructionin which the punch isforced into engagement with the *rough sharp edge 22 by means of springpressure instead of byha-nd pressure. Leversiiii and24 are so formed asto cross over each other andare pivoted together at this point by meansof pivot pin 25. The levers are'forme'd withhandle portions 26 and 21and with forwardly extending arms 28 and 29. Arm 28' carries punchmember9' atqits,

outer end andarm 29 carries the abutment-member I2 at its outer end; Arm28 is also provided with a projection carrying the adjustable screw l8.Theinner surface of arm 28 is pro vided with a socket 30 and the'innersurface of "arm 25! is provided'with a similar socket 3|, these socketsbeing adapted to receive the ends ofan expansicn coil spring '32,biasing arms 28 and--29 apart. In order to limit the extent ofseparationcf the arms, arm 29 has pivoted thereon amember 33 providedwith a slot 34 which receives a stop pin 35 carried by arm 28. Slot'34is of such length that it permits the arms to be moved togethersufficiently that they maybe inserted in the cylinder.

In performing the burring operation with'this tool, handles 26 and 21are forced together by the hand of the operator, thus moving arms 28 and29"toward each other sufficiently that the arms may be inserted in thecylinder and to a point determined by the adjustable screw I8. Withpunch 9' now positioned directly below porthole 20, the hand oftheoperator is permitted to quickly-release the handles, whereby spring 32will rapidly expand and force the annular curved ing off the burrededge.

surface of punch member 9 into engagement with the sharp edge withsufficient force to break for use with a type of cylinder constructionwhich "i'sinserted into a reservoir that completely surrounds the entirecylinder including its open end. Levers 36 and 31 are formed to crossover thereon a small projection 46'. The inner surface of arm carriesthe projecting portion 41 and adjustable screw 48. V

In the operation of this tool, arm 42 is posi tioned in the bore ofcylinder 49 and arm 44 is positioned on the exterior of the cylinder andprojection 46 on abutment member is placed in opening 50, this operationbeing quickly performed by the proper positioning of set screw 48 whichis adapted to abut the inner end of slot 5| formed in the end of thecylinder. The actual I burring operation is now. performed by theoperator forcing handles 39 and 40 together by his hand, thus causingarms 42 and 44 to be moved toward each other forcing the annular curvedsurface of punch member 43 into engagement with the rough edge o-fth'edrilled hole and smooth- The tool is removed by releasing-the pressureon the handles whereby spring 4| will separate arms 42 and 44 suffciently that the projection 46 can be removed from hole 50 and the armswithdrawn.

It is to be noted that the tools shown in Figures 1 and 3 can be usedwith the type of cylinder shown in Figure-4 if such is desired. Theadjustable stop screw employed on all the tools for engagement with theend of the cylinder is not a necessary feature but it has been found tobe very useful in speeding up the work when a large number of the samekind of cylinders are being operated upon since the set screw may begiven an initial setting and the operator will know that when'it is inengagement with the end of the cylinder, the punch member is beneath thehole to be burred. As a substitute for the adjustable stop, the armcarrying the punch may be provided with marks as shown at 5| inFigure 1. When the proper mark for the cylinder being worked upon iseven with the end of the cylinder, the

claim as new and desire to secure by'Letters Patent of the United Statesis:

1. In a tool for smoothing the rough inner edge of an opening in thewall of a cylinder or like article, a pair of relatively movablemembers, an element non-rotatably carried'by one member and having anannular surface adapted to engage the rough edge of the opening, andhand-operated means for moving the members relatively to each otherwhereby one of the members will abut a wall of the cylinder and theannular surface of the element on the other member will be forced intoengagement with the rough edge of the opening to thereby smooth saidedge by direct pressing action.

2. In a burring tool for smoothing the rough edge of a drilled openingin a member, a pair of arms pivoted together, a member provided with anannular curved surface and non-rotatably carried by the free end ofoneof the arms, and means for moving the arms in opposite directions tocause one arm to engage an abutment surface and the curved surface ofthe member on the other arm to be forced against the edge of the openingto thereby smooth said edge by direct pressing action.

3. In a tool for smoothing the rough edge of an opening, a pair ofcooperating arms pivoted together, an element non-rotatably carried byone of said arms adjacent its free end and having an annular curvedsurface, an element carried by the other arm for abutting against asupport, and manually-operated means for moving the arms in oppositedirections whereby the curved surface of the element can be forced intoengagement with the rough edge of the opening and the other element canbe forced intoengagement with a support to thereby cause the curvedsurface to smooth the edge by direct pressing action.

4. In a tool for smoothing the rough inner edge of a drilled opening inthe wall of a cylinder or like article, a pair of levers pivotedtogether and forming a pair of handles and a pair of arms, and a burringelement carried by one of the arms for engagement with the rough edge ofthe opening When the handles are operated by the hand of an operator tocause the other arm to engage a portion of the cylinder wall.

5. In a tool for smoothing the rough inner edge of a drilled opening inthe wall of a cylinder, a pair of levers pivoted together and formin apair of handles and a pair of arms, said arms adapted to be moved inopposite directions by the actuation of the handles by the hand of anoperator, an element having an annular curved surface and carried by oneof the arms for engaging the rough edge, and an abutment element carriedby the other arm for engaging a portion of the cylinder.

6. In a tool for smoothing the rough inner edge of a drilled opening inthe wall of a cylinder, a pair of levers pivoted together and forming apair of handles and a pair of arms, said arms adapted to be moved inopposite directions by the actuation of the handles by the hand of anoperator, an element carried by one of the arms and having a surface forengaging and smoothing the rough edge, an abutment element carried bythe other arm for engaging a portion of the cylinder, and a spring forbiasing the handles apart.

7. In a tool for smoothing the rough inner edge of a drilled opening inthe wall of a cylinder, a pair of levers pivoted together and forming apair of handles and a pair of arms, said arms adapted to be moved inopposite directions by the actuation of the handles by the hand of anoperator, an element having a surface for engaging and smoothing therough edge and carried by one of the arms, an abutment element forengaging a portion of the cylinder and carried by the other arm, aspring for biasing the handles apart, and a stop carried by one of thearms and cooperating with the other arm for maintaining the arms inpredetermined spaced relation.

8. In a tool for smoothing the rough edge of an opening through amember, a pair of levers pivoted together in crossed relation andcomprising a pair of arms and a pair of handles, a member on the end ofone of the arms and provided with a surface for engaging and smoothingthe rough edge, a spring for forcing the arms apart, and means forlimiting the extent of separation of the arms when the handles are freedby the operator.

9. 'In a tool for smoothing the rough edge of an opening through amember, a pair of levers pivoted together in crossed relation andcompris ing a pair of arms and a pair of handles, a mem ber on the endof one of the arms and provided with a surface for engaging andsmoothing the rough edge of the opening, and a coil spring for normallymaintaining the arms in spaced relation.

10. In a tool for smoothing the rough edge of an opening through amember, a pair of levers pivoted together in crossed relation andcomprising a pair of arms and a pair of handles, a member on the innersurface of the end of one of the arms and provided with an annularcurved surface for engagement with the rough edge of the opening,a'projection on the inner surface of the other arm and adapted toproject into the end of the opening opposite the one provided with therough edge, and a coil spring for normally maintaining the arms inspaced relation.

11. In a tool for smoothing the rough inner edge of a drilled opening inthe wall of a cylinder or like article, a pair of levers pivotedtogether and forming a pair of handles and a pair of arms, a burringelement carried by one of the arms for engagement with the rough edge ofthe opening when the handles are operated by the hand of an operator tocause the other arm to engage a portion of the cylinder wall, and meanscarried by one of the arms and adapted to cooperate with the end of thecylinder for indicating the distance that the arm carrying the burringelement should be inserted in the cylinder to be in an operativeposition.

12. In a tool for smoothing the rough inner edge of a drilled opening inthe wall of a cylinder or like article, a pair of levers pivotedtogether and forming a pair of handles and a pair of arms, a burringelement carried by one of the arms for engagement with the rough edge ofthe opening when the handles are operated by the hand of an operator tocause the other arm to engage a portion of the cylinder wall, and anadjustable stop carried by one of the arms and adapted to engage the endof the cylinder for predetermining the distance that the arm carryingthe burring element may be inserted in the cylinder.

13. In a tool for smoothing the rough inner edge of a drilled opening inthe Wall of a cylinder, a pair of levers pivoted together and forming apair of handles and a pair of arms, said arms adapted to be moved inopposite directions by the actuation of the handles by the hand of anoperator, an element carried by one of the arms and having a surface forengaging and smoothing the rough edge, an abutment element carried bythe other arm for engaging a portion of the cylinder, and an adjustablestop carried by one of the arms for engagement with an end surface ofthe cylinder.

ALBERT BRUNNER.

